“Using natural based plasticizers to obtain flexible PVC  low environmental impact "

Summary
During the last years in the plasticized PVC industry there is some controversy with the use of traditional plasticizers based on phthalate, and used widely in the industry. Although it has not been completely demonstrated, this type of plasticizers presents a toxic potential risk if they can migrate to the materials by which they are in contact with.  For this reason it has been limited the use of plasticizers in these sectors, such as the food packaging or the toy sector, in which this product is in direct contact with food or with children. However, in these sectors, the use of plasticized PVC in practice is essential due to the balance of properties that the materials have and the specificity of its manufacturing processes. For this reason researches with alternative free phthalates plasticizers are carried out.
One of the opened lines of research is the use of natural based plasticizers from natural origin and low toxicity. In this doctoral thesis three plasticizers have been chosen for natural based PVC and low toxicity: two epoxidized fatty acid esters plasticizers and epoxidized linseed oil. The overall aim of this thesis is to determine whether natural plasticizers are a real alternative to traditional methods based on phthalate plasticizers. Thus, we have carried out a series of analysis and tests to determine the feasibility of using this type of plasticizer in the industry.
First, an optimization of curing parameters has been carried out to determine whether these conditions are compatible with current manufacturing processes used in industry. We have chosen an amount of  70 phr (per hundred resin) of the different natural based plasticizers; this formulation is commonly used in industry. Obtaining the optimal curing parameters is based on the optimization of mechanical, thermal, morphological and colorimetric properties. The obtaining of the parameters of the ideal curing parameters has been based on the optimization of his mechanical, thermal, morphologic and colorimetric properties. In addition, standard migration tests have also been carried out according to standard to assess the amount of plasticizer that can migrate to the medium where it is in contact with under certain conditions.
Once the cured optimized parameters are obtained, we evaluate the influence of the amount of plasticizer on the mechanical, thermal, morphological and visual appearance of the different plastisols obtained with the three plasticizers used in this work. A greater amount of plasticizer is associated with an increase in the flexibility of the material, decreasing its tenisle strength and increasing elongation. 
It is also emphasized that the mechanical properties achieved, although slightly minor than those obtained with some traditional plasticizers, all three plasticizers are perfectly valid for the manufacture of the range of standard products made from flexible PVC